Apparatus is described including a blood pump (27) that includes an impeller (50) that has proximal and distal bushings (64, 58), and is configured to pump blood. A frame (34) is disposed around the impeller (50), a proximal bearing (116) is disposed proximally and a distal bearing (118) is disposed distally with respect to the impeller (50). An axial shaft (92) passes through the proximal and distal bearings (116, 118) and the proximal and distal bushings (64, 58). The axial shaft (92) is coupled to at least one of the proximal and distal bushings (64, 58) of the impeller (50), such that the at least one bushing is held in an axially-fixed position with respect to the axial shaft (92), and is not held in an axially-fixed position with respect to the proximal and distal bearings (116, 118). Other applications are also described.
